Turn screw adjusts pressure to fit work and stays adjusted for repetitive use Constructed of high-grade heat-treated alloy steel for durability Classic trigger release designed to provide maximum locking force The Locking Chain Clamp is perfect for clamping irregularly shaped objects up to 18 inch in circumference We provide 24-hour after-sales service,if you have any questions or suggestions,please feel free to contact us,we will reply as soon as possible